This invention relates to a rechargeable lead acid battery cell and, more particularly, to such a battery cell which is leak-proof while allowing venting of gas from the cell and which is in a small housing of such size and shape and with terminal placement such that the inventive battery cell can be used as a replacement for conventional portable batteries, such as used, for example, in flashlights and the like.
There exists a need for an inexpensive rechargeable battery cell of the type which can be used in consumer appliances such as flashlights, portable radios, portable tape players, and the like. While effective, nickel-cadmium battery cells are expensive and also must be fully discharged before being recharged. At the present time, lead-acid batteries, such as the type used in automobiles, are relatively inexpensive and can be recharged at any point in their discharge cycle. However, such batteries contain an acidic electrolyte solution. For use in a consumer appliance, the battery cell must be designed to prevent the electrolyte solution from leaking out of the battery housing, irrespective of the orientation of the battery cell. Further, if a lead-acid battery is overcharged, the resultant heat causes gas to be generated which can cause the battery to explode. If the gas is allowed to vent to prevent such an explosion, the electrolyte solution must be replenished. It is therefore an object of the present invention to provide a leak-proof rechargeable lead-acid battery cell which also allows gas to be vented therefrom and the electrolyte solution to be replenished.